and also extreme dense shadows where you cant realy see nothing

or when you are down the structure extreme weird effect

1: clouds can be rendered in front, if you enable the "render clouds in front of world" misc settings, however, it doesn't work very well.

2: thats vanilla Minecraft behavior, the flying island will make it darker below it.

3: that is cave fog. i cannot accurately tell when or where a cave is, so unfortunately this is a scenario where it does not work the best.i olan to improve this a little at some point. you can disable cave fog in the fog settings.

And some times everything i so black that i cant se absolutely 0 how i can increase that light at least like vanilla

Ok i just changed ambient light